The Stepper controls operate as described below. Recall that the current position is always highlighted in orange:

Step

Steps once, remaining inside the current form. At the start of the current form, this steps the first inner form. At a function call, it steps to the value. At the form value, it steps the next form or value.

Step Through Call

Steps once. This is the same as Step above, except that at a function call, it steps that function if the source is known.

Step To Call

At the start of a form, steps to the function call of that form after evaluation of the arguments. At a function call or at the end of a form, steps to the function call of the enclosing form.

Step To Value

At the start or function call of a form, steps to the value of that form. At the end of a form, steps to the value of the enclosing form.

Next

Steps to the start of the next form, or behaves like Step if there is no next form.

Step To End

Steps to the value of the current function.

Step To Cursor

Steps to the cursor position, or displays a message if that position is not steppable.

Continue

Runs the code until a breakpoint is reached.

Breakpoint

Sets a breakpoint at the position of the cursor if there is no breakpoint there already and the position is steppable. If there is a breakpoint under the cursor, this command removes it. Note that breakpoints are highlighted red, though the orange highlight on the current stepping position overrides any breakpoint highlight..

Show Current Source

Moves the editor buffer in the source area so that the definition at the top of the backtrace area, and the active form within it, is visible.

Macroexpand

Macroexpands the form under the cursor.

Undo Macroexpand

Collapses the macroexpansion under the cursor.

Abort

Aborts the execution and returns to the form which you first stepped, allowing you to repeat the execution or edit the form. This command is available only when using the Stepper in standalone mode.